A) Field of the Invention
This invention relates to a semiconductor chip, especially relates to a flip-chip mounted chip that a solder bump is formed on a silicon substrate and that is directly mounted on the substrate.
B) Description of the Related Art
It becomes necessary that a semiconductor chip is mounted in high density on the substrate by miniaturization of an electronic device using a semiconductor chip in recent years. Therefore, as shown in FIG. 6A and FIG. 6B, it is common that connecting electrodes (solder bumps) 60 are formed on a semiconductor chip 51, and the semiconductor chip 51 is directly connected to substrate lands 71 formed on a circuit substrate 70 via the solder bumps 60 by the so-called flip-chip mounting.
When the above-described semiconductor chip 51 is equipped on the circuit substrate 70, generally positioning is executed by an automatic mounting device, and the semiconductor chip 51 is mounted on the circuit substrate 70. Then for example, the semiconductor chip 51 is equipped by executing a solder reflow process of 220 to 250 degrees Celsius.
A mounting size (contacting size) between the solder bump 60 that is an electrode at the parts side and the substrate land 71 that is at the substrate side is very small such as several tens to hundreds micrometer, and there is a risk for a positioning gap.
It is suggested that the positioning gap can be corrected by self-adjustment wherein the center of the solder bump at the substrate side and the center of the solder bump at the chip side are formed shifted with each other (for example, refer to Japanese Laid-Open Patent Hei6-132353). Also, it is suggested that inclination of the chip is prevented by the reflow (for example, refer to Japanese Laid-Open Patent Hei9-250429).
Moreover, as described in the above, since the mounting size is very small, it may be broken by vibration given at a time of transportation to the next process of mounting or stress at a time of handling. Also, a mounting error may occur by a bend of the parts and substrate caused by the heat stress at a time of mounting.